Why is my camera alternating between two image brightness levels?

[Cyrano]

I've set one Arlo Q camera behind a window, to observe my front porch.

The night vision on this camera is disabled.

At night, with my porch light on, things seem fine:

   https://arlo.netgear.com/hmsweb/users/library/share/link/B0193CFEFFAD25FD

But when I turn off the porch light, the camera won't hold a constant brightness level. Instead, it alternates between two brightness levels, at a frequency of about once per second:

   https://arlo.netgear.com/hmsweb/users/library/share/link/61EA07F41AC4E779

Any ideas on what is causing this weird behavior?

[jguerdat]

It looks like a light is turning on and off but there's the noise that may be causing it.  Is there something nearby that could be causing the noise or is it the camera? I don't know why that would be causing a change in brightness unless there really is a light doing that.  

Is your microphone enabled? Try disabling it.  Both night vision as well as the mic are disabled on my Q pointed through a window and don't display this behavior.

[TomMac]

To me it looks like the camera is on the edge of iris sensitivity and filp flopping back and forth to B/W mode.

To fix , go to live mode and adjust the iris level ( looks like a small sun on the live view screen bottom when viewing ).  It gives a  + and - adjustment for light.

If that doesn't work, I'd reset the camera and test again.

[jguerdat]

Worth a try but I don't see color in either version. My cameras are very definite when switching in and out of B&W.

[Cyrano]

@jguerdat: The sound you hear on the video is coming from the camera itself, as something in its internal mechanism is toggling on and off.

@TomMac: Interesting idea! I'll test this hypothesis this evening.